A 

HANDBOOK 

FOR 

DAIRYA^EN 



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A HANDBOOK FOR DAIRYMEN 



THE RELATION 

OF 

TEMPERATURE, HUMIDITY 
AND PRESSURE 

TO 

DAIRY OPERATIONS 

A HANDBOOK FOR DAIRYMEN 

By 

WALTER WrFISK, M.S. IN AGR. 

Professor of Dairy Industry, New York State 
College of Agriculture, Cornell University 



FOXBORO, MASS. 
THE FOXBORO CO., Inc. 

Neponset Avenue 






Copyright, 1922 
By The Foxboro Co., Inc. 



First Edition, July, 1922 



THE UNIVERSITY PRESS, CAMBRIDGE, U. S. A. 



JCI.A(I81323 



m "5 iy22 



:? FOREWORD 

^ 'TT^HE object of this book is to provide authorita- 

I tive and up-to-date information on the relation 
of temperature, humidity and pressure to the 
manufacture of dairy products. 

Because of his professional standing and wide ex- 
perience with every phase of the dairy industry, 
Professor Walter W. Fisk, of Cornell University, 
was asked to prepare the material. 

Professor Fisk is in no way connected with The 
Foxboro Co., Inc., and no restriction of any kind 
was imposed upon him. He was at liberty to write 
what he wished. Each branch of the dairy industry 
has been analyzed from the standpoint of tempera- 
ture, humidity and pressure, and discussed in the 
light of the best practices of the most successful 
dairymen. No theories that have not proved to be 
commercially practical are presented. 

The result is an unbiased, authoritative treatise 
on some of the most significant phases of dairy 
operation. 

With the hope that we have contributed to dairy 
improvement and progress this book is dedicated to 
the dairy industry. 

THE FOXBORO CO., INC. 

July 1, 1922 



TABLE OF CONTENTS 

Chapter Page 

I. Introduction 1 

II. Bacteriology 9 

III. Butter Making 19 

IV. Milk and Cream 26 

V. Ice Cream 39 

VI. Condensed and Evaporated Milk .... 48 

VII. Milk Powder 56 

VIII. Cheese 59 

IX. Casein and Milk Sugar 65 

X. The Power Plant 67 



CHAPTER I 

INTRODUCTION 

It is only recently that the importance of tempera- 
ture, pressure and humidity in relation to milk 
handling has been fully realized. Authorities are 
now agreed that the successful manufacture, han- 
dling and storage of milk and milk products of prime 
quality depend upon the knowledge and the careful 
regulation of these factors. Cleanliness is not to be 
minimized, but it is taken for granted in this dis- 
cussion that every right-thinking dairyman has the 
welfare of his community enough at heart to use the 
utmost care in keeping his plant clean and sanitary. 
Our aim is to give to the manufacturer, superin- 
tendent and operator certain suggestions regarding 
the relation of temperature, humidity and pressure 
to dairy operations, which will not only enable him 
to raise the standard of his product and eliminate 
needless wastes, but in the end will be of assistance 
to the whole industry. 

Temperature has two influences on dairy opera- 
tions: it regulates the growth of micro-organisms, 
and it has a physical effect on certain operations 
and on the quality of the finished product. 

The Influence of Temperature on the Growth of 
Micro-Organisms . 
Every dairyman knows that in milk and milk 
products there are many micro-organisms : bacteria, 
yeasts and molds. Because these are really tiny 
plants, their growth depends upon a readily avail- 
able food supply and proper temperature. Milk and 



2 A Handbook for Dairymen 

milk products furnish their food, but high tempera- 
ture will kill them and low temperature will retard 
their growth. 

Professor W. A. Stocking in an interesting ex- 
periment shows the effect of temperature on the 
development of bacteria in milk. A sample of milk 
was thoroughly mixed and divided into six equal 
parts. The six bottles were placed in water at dif- 
ferent temperatures for twelve hours, at which time 
the germ content of each lot was determined. The 
bottles were then all placed together in a tempera- 
ture of 70° F. and allowed to remain until they 
curdled. As each sample curdled, the time was re- 
corded. Results show what may happen easily in 
milk which is allowed to stand overnight without 
thorough cooling. 

Effect of Different Temperatures, Maintained for 

Twelve Hours, on the Growth of Bacteria and on the 

Keeping Quality of Milk 

I II 

Kept at 45 degrees Kept at 50 degrees 

Number of bacteria, 9300 Number of bacteria, 18,000 

Curdled in 75 hours Curdled in 72 hours 

III IV 

Kept at 55 degrees Kept at 60 degrees 

Number of bacteria, 38,000 Number of bacteria, 453,000 

Curdled in 49 hours Curdled in 43 hours 

V VI 

Kept at 70 degrees Kept at 80 degrees 

Number of bacteria, 8,800,000 Number of bacteria, 55,300,000 

Curdled in 32 hours Curdled in 28 hours 

In cheese and butter making, the growth of cer- 
tain types of organisms, especially the lactic acid 
type, is essential. In other dairy operations, such 
as the handling of market or fluid milk, condensed 
milk and evaporated milk, the growth of organisms 
invariably causes the product to spoil. 



Introduction 



All dairymen and milk producers probably make 
use of these facts, and the most successful cool the 
milk as soon as it is drawn from the cow. Regard- 
less of how clean the milk may be produced, there is 
certain to be some micro-organisms in it. Of course 
some of these are beneficial and others are harmful, 
but as the producer cannot distinguish between them, 
the development of all should be retarded by cooling 
and holding cold. 

The Influence of Temperature on the Qutdity of the 
Finished Product. 

The quality of the finished product is judged by 
its flavor, body, texture and appearance. 

Flavor is affected by bacterial growth, and this 
growth in turn is regulated by the temperature. A 
high temperature will cause a bad or undesirable 
flavor. A low temperature may cause a lack of 
flavor. 

The body and texture and appearance are deter- 
mined by the moisture content and the process of 
manufacture. Both are largely regulated by tem- 
perature. For example, if cheese is heated too high, 
it will be dry, hard and crumbly, while ice cream 
that is not frozen sufficiently will be watery and 
grainy. The churning of cream into butter depends 
upon the correct churning temperature. If the 
cream is too warm, the butter will be too soft and 
will have a very poor body ; if too cold, it will not 
churn at all, or very slowly. 

The successful manufacturer must make a prod- 
uct that is uniform from day to day. Uniformity 
depends upon many factors, but the important one, 
as will be pointed out in detail later, is that of the 
correct temperature. 



A Handbook for Dairymen 



The Inflitence of Temperature on the Storage of 
Dairy Products. 

The keeping quality of milk or milk products de- 
pends largely upon a uniform holding temperature. 
If the temperature is allowed to go too high or 
to fluctuate from day to day, the product will not 
keep as long as when held constantly at the proper 
temperature. 

When butter and cheese are held in a refrigerator 
and the temperature rises, they not only deteriorate 
in flavor and body and texture, but molds grow 
rapidly and injure the quality. Bad flavors and 
poor body and texture in practically all dairy prod- 
ucts quickly develop under poor storage conditions. 

Many losses can be positively attributed to im- 
proper storage temperatures. For example : The 
writer knows of one case in which an ice-cream 
manufacturer lost his entire business because of 
the poor quality of his ice cream. The ice cream 
was of good quality when it left the freezer, but be- 
came grainy and icy during the hardening process, 
due to uneven and, at times, too high a temperature. 

Another case of loss is that of the storage of 
butter. A thousand tubs of butter were held in a 
storage which occasionally became too warm and 
damp so that molds rapidly grew. In this case, 
each tub had to be stripped and the mold scraped 
off. The butter sold at a loss of ten cents a pound, 
or about six dollars a tub, because of the moldy 
flavor. A loss of six thousand dollars could have 
been avoided if only a very small fraction of that 
sum had been invested in a recording thermometer. 

There is no definite length of time that a product 
may be held in storage without deteriorating. 
Time of deterioration depends upon the quality of 
the product when put in and the temperature of 



Introduction 



storage. Whenever the temperature rises during 
storage, if conditions are right, it gives the lactic 
acid-forming bacteria a chance to develop. This is 
especially true of fluid or liquid milk and unsweetened 
condensed milk. These products sour quickly in a 
refrigerator that is not held at a uniform cold 
temperature. 

The Influence of Humidity on Dairy Products. 

Humidity is most important in the ripening of 
cheese, the manufacture of milk powder and the 
storage of products not hermetically sealed. The 
correct humidity is necessary for the proper func- 
tioning of the ripening agent during cheese curing. 
If the humidity is too low, there will be too much 
evaporation, which will cause unnecessary losses. If 
too high and accompanied by the correct tempera- 
ture, molds will grow and spoil the product. If the 
humidity is too high, it is impossible to make good 
milk powder after certain processes. 

The Influence of Pressure on Dairy Products. 

It is very necessary to have a constant steam 
pressure for the successful operation of many ma- 
chines. For example: the centrifugal separator. If 
there is not sufficient steam pressure, the efficiency of 
the machine is reduced. It is also important to have 
different materials put through machines at a given 
pressure. For example : ice cream mixed through 
the homogenizer. If the pressure is reduced, the in- 
tended results are not accomplished. The important 
subject of power-plant efficiency will be discussed in 
a separate chapter. 

As stated above, the quality and salability of 
dairy products depend upon a careful regulation of 
temperature, pressure and humidity. Manufactur- 



6 A Handbook for Dairymen 

ing and storage losses can be traced directly to a 
lack of knowledge, or to inadequate means of 
controlling these factors. Savings can be made in 
formerly wasted materials, steam and water. Losses 
can be turaed into profits. The vital relationship 
of temperature, pressure and humidity to each dairy 
product will be discussed in the following chapters. 




View of one of six temperature-control boards with recording 
thermometers for incubation rooms in Pathological Division, Bureau 
of Animal Industry, U. S. Dept. of Agriculture. Foxboro Ther- 
mometers of the continuous seven-day type are used. 



CHAPTER II 

BACTERIOLOGY 

The control of temperature within close limits is 
very important in laboratories where bacteriological 
investigations of the micro-organisms of dairy prod- 
ucts are conducted. In many instances the success 
in the maintenance of cultures depends upon the 
ability continuously to maintain a constant tem- 
perature. 

The micro-organisms of dairy products are grown 
on various food materials known as media. To se- 
cure the proper temperature for growth they are 
usually placed in an insulated box known as an in- 
cubator, and the temperature is regulated by an 
electric thermostat, fan and ice. 

Each incubator is usually fitted with a seven-day 
recording thermometer. The recording elements are 
mounted on the wall outside of the incubator and 
the capillary tube passes through the wall, the bulb 
being located near the top and in the center of the 
incubator. The charts taken from the recorder are 
examined and any variations in temperature be- 
yond the prescribed limits are noted, with the time 
at which the variations occurred. 

The value of a continuous temperature record in 
the process of incubating cultures lies in the fact 
that such records not only show the temperature at 
all times throughout the period of incubation, but 
they are dated and can be filed for reference. It is 
thus possible to determine with accuracy the tem- 
perature maintained in the incubating process on 
any previous date. 



10 A Handbook for Dairymen 

If the temperature in the incubator is too low, 
the growth of the organism will be very slow, or it 
will not grow at all. Also if the temperature is too 
high, the organism may not grow. In either case 
if it does grow, it will not give a strong type and 
contaminations are likely to appear. 

Starter. 

A practical application of bacteriology to dairy 
operations is the preparation of starter.* The 
lactic acid starter used in the making of butter and 
cheese is the most common. Other starters are the 
molds of Camembert and Roquefort cheese, Bulgari- 
cus for Swiss cheese, the eye-forming culture for 
Swiss cheese, and the starter for ripening cream for 
Hebrew trade. 

The Lactic Acid Starter. 

Since cultures must be prepared by a bacteriolo- 
gist, commercial laboratories have developed a large 
business in their production, usually under trade- 
marked names. Some of these cultures represent 
races of lactic bacteria cultivated and cared for 
efficiently, hence uniformly valuable over long 
periods of time. Others, carelessly produced, are 
worthless, or even a peril to the user. 

The organisms are usually shipped in small 
quantities in bottles of liquid or powder, or in cap- 
sules of uniform size. The contents may be either 
the culture medium upon which the organisms grew, 
or an inert substance designed merely to hold the 
bacteria in active form. In either solid or liquid 
form, the producer of the culture should guarantee 
its activity up to a plainly stated date. 



•Starter 13 a culture of desired organisms in a living or active 
state. 



Bacteriology 11 



It is the problem of the cheese or butter maker 
first to keep the organisms pure, and second to in- 
crease them to such numbers and in such an active 
condition that they are commercially useful. The 
common practice is to allow them to develop in some 
material, usually whole milk or skimmed milk, or 
even dissolved milk powder. 

The manufacturer's directions apply to average 
conditions and must be varied to suit the individual 
case. The directions should state the amount of 
milk necessary for the first inoculation, usually one 
or two quarts. 

Suggestions for Selecting Starter Milk. 

As the flavor of the starter will be the same as 
that of the milk from which it is made, great care 
should be used in its selection. The following sug- 
gestions are offered to aid in this selection: only 
clean-flavored sweet milk, free from undesirable 
micro-organisms, should be used. Choose the morn- 
ing milk because the bacteria have not had much 
chance to develop. In no case should mixed milk be 
used, as this eliminates all opportunity for selection. 
Choose the milk from a producer who maintains 
high standards and whose milk is usually in good 
condition. The quality of the milk can be deter- 
mined by the fermentation test. 

Pasteurization. 

Pasteurization kills most of the micro-organisms 
in the milk and makes a clean seed-bed for the pure 
culture. The temperature of pasteurization recom- 
mended for starter making differs with the author- 
ity. A temperature of 180° F. for thirty minutes or 
longer seems to be very satisfactory because under 



12 A Handbook for Dairymen 

these conditions nearly all the micro-organisms are 
killed. 

The small amount of milk needed for starter 
making may be pasteurized by placing the container 
in water heated to the desired temperature. A very 
satisfactory arrangement is to cut off a barrel and 
place a steam pipe in it. Two or three extra 
bottles should be prepared, as some of them may be 
broken. Fill the bottles about two-thirds full so 
that there will be room enough for the mother 
starter and for later examination. To avoid pos- 
sible contamination, it is desirable not to have the 
milk or starter touch the cover. It is a good plan 
when pasteurizing to have one bottle of water as a 
check. Test the temperature for all the bottles by 
inserting a thermometer in the bottle filled with 
water. Never put a thermometer in the starter 
bottles. Uniform temperature may be obtained by 
shaking. 

Cleanliness. 

A successful starter can only be made if all uten- 
sils coming in contact with the milk are sterile. Keep 
the covers on the containers at all times. Don't put 
thermometers into the bottles. When examining the 
starter, pour it out — never dip into it. If the 
cover is removed from the container, put it in a 
sterile place. It is easy to spoil the culture if the 
cover becomes contaminated. 

Glass fruit jars, or quart milk bottles, or tin 
containers may be used for starter making. The 
first two are more easily cleaned and their content is 
always visible, but they break easily. The tin con- 
tainer does not break, but it is hard to keep clean 
and the chance for contamination is exceedingly 
great. 



Bacteriology 13 



Adding the Culture. 

After being pasteurized, the milk should be cooled 
to a temperature of 80° F. — a suitable temperature 
for the development of the lactic acid-forming or- 
ganisms. The commercial or pure culture is added 
to the milk and mixed thoroughly by shaking the 
bottle. The shaking should be repeated four or five 
times every fifteen or twenty minutes. The milk 
should be placed in a room or incubator with a tem- 
perature as near 80° F. as possible. A uniform 
temperature is necessary for the growth of the or- 
ganisms. The bacteria in the pure culture are more 
or less dormant, so that this higher temperature is 
necessary to stimulate their activity. The milk 
should be coagulated in eighteen to twenty-four 
hours, depending largely on the uniformity of the 
temperature maintained in the incubator. 

"Mother" Starter, or Startolme. 

The thickened sour milk obtained by inoculating 
the sweet pasteurized milk with the pure culture of 
lactic acid-forming bacteria is known as " Mother '* 
starter, or Startoline. Its physical properties, odor 
and taste should be examined carefully. 

Sometimes the first few inoculations from a new 
culture will show signs of gas, but ordinarily this 
will quickly disappear and have no injurious effect 
on the starter. It should have a clean sour-cream 
odor and be smooth, thick and creamy, entirely free 
from lumps, whey, and gas pockets. This starter 
may have an objectionable flavor, due to the media 
in which the organisms were growing when shipped. 
In such cases it is necessary to carry one or two 
propagatipns to overcome the flavor, to enliven the 
micro-organisms %nd to secure the quantity desired. 



14 



A Handbook for Dairymen 




A Foxboro Recording Thermometer installed on the exterior 
of a bacteriological cold storage vault. The tube connecting 
the bulb passes through the wall. Permanent records of the 
exact temperature are thus maintained and unnecessary open- 
ing of the door to the vault is eliminated. 



TJie Second Day's Propagation. 

For the second day, the milk for the starter is 
selected as on the first day. It is pasteurized, and 
this time is cooled to 70° F. because the organisms 
have become more active, and hence do not require so 
high a temperature to grow. Instead of inocu- 
lating with powder, as was done the first day, the 
mother starter already prepared is thoroughly 
mixed with the milk. Only a very small amount is 
required, perhaps a tablespoonful to a quart bottle. 
Since this starter may have the flavor of the media 
used in the laboratory culture, it may be necessary 
that it be carried one or two days more to eliminate 
it. After the flavor has become normal, the mother 
starter is ready for use. 



Bacteriology 1^ 



Preparation of Larger Amou/nts of Starter. 

Determine the quantity of starter required, select 
the milk as carefully as before, pasteurize, cool and 
add the mother starter. 

The milk should be pasteurized at a temperature 
of 180° F. for thirty minutes if possible. A good 
incubation temperature is 60° to 65° F. However, 
this temperature may be varied so that the starter 
will be ready at a given time — the higher the tem- 
perature the less time is required to ripen the 
starter. 

Pasteurization and incubation can be carried on 
in a starter can or a milk can. The former requires 
mechanical power to operate the agitator. The 
latter may be used where mechanical power is not 
available, and the milk and starter is stirred by 
hand. This kind of apparatus is more often used 
in cheese factories. 

Amount of Mother Starter to Use. 

Use the mother starter prepared the day before. 
The amount depends upon the following factors : 

1. Temperature of milk when mother starter is 
added. 

2. Average temperature at which the milk will be 
kept during the ripening period. 

3. Time allowed for the starter to ripen before it 
is used. 

4. Vigor and acidity of the mother starter added. 

The amount of starter may vary from 0.5 per cent 
to 10 per cent, depending upon the above conditions. 

Some operators prefer to add the mother starter 
while the milk is at a temperature of about 90° F., 
before it has been cooled to the incubating tempera- 



16 A Handbook for Dairymen 

ture. This reduces the amount of mother starter 
necessary. 

If an even incubating temperature can be main- 
tained, less mother starter is needed than if the 
temperature goes down. 

If the ripening period is short, it will require a 
larger amount of mother starter. If the starter has 
a low acidity or weak body, indicating that the or- 
ganisms are of low vitality, more will be required. 

The starter, when ready for use, may or may not 
be coagulated. A good idea of the quality of the 
starter may be gained by the condition of the 
coagulation. It should be jelly- or custard-like, close 
and smooth, entirely free from gas pockets, and 
should not be wheyed off. 

When broken up, the starter should be of a smooth, 
creamy texture and entirely free from lumpiness or 
wateriness. It should have a slightly pronounced 
acid aroma. The flavor should be clean, mildly acid 
and free from all undesirable taste. 

Bulgaricus Starter. 

The Bacillus Bulgaricus Starter for Swiss cheese 
is carried in about the same way as the lactic acid 
starter, except that whey is a more desirable medium 
than milk. This organism requires a temperature 
of 100° F. for growth. 

The growing of the molds for Camembert and 
Roquefort cheese is somewhat similar, except that 
Camembert is aerobic and grows on the outside of the 
cheese, while the Roquefort is anaerobic and grows 
on the inside of the cheese. The Camembert mold 
may be grown on a media of whey agar or on sterile 
crackers. It grows spores more rapidly when held 
at a temperature of 60° to 70° F. It should also be 
kept very moist. The Roquefort molds grow best 



Bacteriology 17 



when inoculated into a fresh loaf of bread that has 
been paraffined as it comes from the oven. As soon 
as cooled, it is ready for inoculation. This can be 
done by drawing the mold spores with sterile water 
into a sterile pipette and then forcing them into the 
bread. The loaf should be sealed and held at a 
temperature of 60° to 70° F. 

Experiments are now being conducted on the eye- 
forming culture for Swiss cheese. The fact is known 
that such a culture exists, but definite information is 
lacking as to its preparation and handling. 

Com/mercial Buttermilk. 

Commercial buttermilk is the term applied to 
lactic acid starter used for drinking. It is often 
sold as buttermilk or prepared buttermilk, and 
under many trade names, such as Lactic Culture, 
Bulgazoon and the like. It is made in the same way 
as any starter up to the time it begins to coagulate. 
As soon as it is coagulated and before the coagula- 
tion becomes too hard it must be broken up. If 
allowed to become too hard, the buttermilk will be 
lumpy and will whey off very rapidly — a great ob- 
jection to it. As soon as coagulated the starter 
should be churned. The flavor is improved if 10 
or 15 per cent of sweet whole milk is added and 
churned with the starter. As soon as churned, it 
should be placed in a ripener or other suitable con- 
tainer and rapidly cooled to 40°— 50° F. and held 
at this temperature. If allowed to warm up and 
cool again, it will whey off much more rapidly. As 
soon as cooled it is ready for consumption. It may 
be sold in bulk in 40-quart cans or put up in various- 
sized milk bottles. Commercial buttermilk should 
have a desirable mild acid flavor, a smooth, creamy 
body and texture, and should not have free whey. 



CHAPTER III 

BUTTER MAKING 

The a B C's of butter making are separating the 
cream from the milk, preparing the cream for churn- 
ing or ripening, churning, packing and storing; 
five simple steps full of pitfalls for the unwary. 
What are the precautions to be taken ? How can 
losses be avoided ? How can savings be made by the 
proper regulation of temperature and pressure? 
After studying the manufacturing methods of many 
of the most successful butter makers of the country, 
a few of the factors which enable the butter maker 
to manufacture consistently a uniform product of 
high quality will be set forth. 

Separating the Cream. 

If the cream separator is working efficiently there 
should not be more than .01 to .02 per cent of fat 
left in the skimmed milk. The efficiency of the ma- 
chine depends upon the following factors : 

1. Temperature of milk being separated. If the 
separator is set up properly, temperature is the 
factor which is most likely to affect the ef- 
ficiency of the machine. If the temperature is 
below 85°-100° F. the separator will not re- 
move all the fat. 

2. Speed of the separator. If belt driven, keep 
the belt tight. If turbine driven, the proper 
speed can be insured by placing a pressure 
gauge in the steam line. It must be remem- 
bered that if the separator is not operated at 
the specified speed, it will not skim clean. 

3. Rate of flow of milk. Operate the separator to 



20 A Handbook for Dairymen 

capacity and keep the feed cup filled to the 
level indicated by the maker. 

4. Percentage of fat in the cream. Sometimes a 
cream rich in fat will not be skimmed clean. 
Butter makers differ as to the desirable fat con- 
tent but a cream testing 30—35 per cent fat will 
give satisfactory results. The separator will 
not always deliver cream containing exactly the 
same percentage of fat, even if the cream screw 
is adjusted properly. If an exact percentage of 
fat is desired, it can only be secured by stand- 
ardizing, (For method of standardizing, see 
page 31.) 

5. Amovmt of slime in bowl. 

Most butter makers install a pre-heater to heat 
the milk to the proper separating temperature. It 
is desirable to connect a recording thermometer to 
the pre-heater. This gives the operator an accurate 
working guide and the management a check on 
operating conditions. 

Pasteurization. 

There is no " best practice " in regard to pasteur- 
ization. There are pro-pasteurizers and those who 
are against it. Those that favor pasteurization 
base their judgment on the fact that it eliminates 
the possibility of disease and that it usually im- 
proves the flavor of the butter. A temperature of 
145° F. for thirty minutes has proved to be very 
satisfactory. However, if cream is pasteurized at 
too high a temperature, the butter is likely to have 
a cooked flavor. After pasteurization the cream 
should be cooled to the ripening temperature of 60° 
to 75° F. 

Preparing the Cream for Churning — Ripening. 

Good judgment of the butter maker and the taste 
of the consumer usually determine the method of 



Butter Making 21 



preparing the cream for churning. The various 
methods of preparation are as follows : 

1. The cream may be pasteurized, if sweet, held 
cold and churned sweet. 

2. Pasteurized, starter added and churned. 

3. Neutralized and not pasteurized, starter added 
and churned. 

4. Neutralized, pasteurized, starter added and 
churned. 

Sweet cream should be pasteurized before churn- 
ing, or there will be a large fat loss in the but- 
ter-milk. Cream that is churned sweet makes a 
milder-flavored butter and keeps better in storage. 

Amount of Starter. 

No definite rule can be stated as to the amount of 
starter to add, as it will vary from 1 to 30 per cent. 
The proper amount depends upon the length of time 
the cream is ripened, the ripening temperature, the 
acidity of the starter and the acidity desired in the 
cream at the time of churning. The amount of acid 
or degree of ripeness is determined largely by the 
amount of fat in the cream. The more fat the less 
acid is required. The cream when ready to churn 
should have 0.3 to 0.65 per cent acidity. 

There is no definite time when the starter is 
added. Some butter makers prefer to add it when 
the cream is partially cooled, usually from 75° to 
90° F. The cream must be cooled below the tem- 
perature at which the lactic acid organisms are 
killed before the starter is added or its effect will be 
lost. Others prefer to add it after the cream is 
partially cooled. Lumps of starter cause white 
specks in the butter. Therefore, the starter should 
be strained. 



22 A Haiidhook for Dairymen 

After being ripened the cream should be cooled to 
the churning temperature or slightly below and held 
for at least three or four hours. This allows the 
fat globules to congeal. 

It is obvious that successful ripening and pas- 
teurization hinge upon the careful regulation and 
control of temperature while the cream is in the coil- 
ripening vat. Even the experienced operator should 
have an accurate guide at this critical stage. Re- 
gardless of the size of the creamery, it has been 
proved that the installation of a recording ther- 
mometer not only helps to standardize the quality 
of the product, but points \he way to savings worth 
many times the cost of the instrument. 

Churning. 

If the butter is to be colored, it is desirable to add 
the coloring to the cream either just before or im- 
mediately after placing the cream in the churn. Some 
makers prefer to add the color to the salt. However, 
it is difficult to obtain a uniform color by this method. 
The amount of color to use varies from 1 to 3 ounces 
per 100 pounds of fat. 

Churning time is determined by the temperature 
of the cream. The churning temperature varies 
from 48° to 65° F. according to the season of the 
year, being lower in summer than in winter. If 
churned too warm, the butter will come very quickly 
and will be too soft. If too cold, it will come very 
slowly and the granules will not gather easily. The 
butter should be churned until the granules are 
about the size of kernels of wheat. This should 
require thirty to sixty minutes. 

After the buttermilk is drawn off, the butter 
should be washed with water at the same temperature 
as the buttermilk. If the butter is very soft, colder 



Butter Making 23 



water may be used to make it firm. It is advisable 
to wash the butter in two waters to remove any re- 
maining buttermilk. The churn should be given 
several revolutions in each water. 

Butter may be marketed either with or without 
salt. That without salt is known as sweet butter, 
and is demanded especially by the Hebrew trade. 
The amount of salt to add varies from 1.5 to 5 per 
cent, depending upon the taste of the consumer. It 
is advisable to add the salt while the butter is yet 
in the granular condition. 

Working distributes the salt evenly, presses out the 
free buttermilk, gives the butter a solid body, the 
desired texture or grain and a uniform color, and 
also incorporates the moisture. If worked too much 
the butter will be greasy or salvy and the texture 
injured. If not worked enough, the color will not 
be uniform and the body will not be solid. 

The increase of the butter over the butter fat is 
due to the incorporation of moisture and is known 
as over-run. It is the aim of every butter maker to 
secure as large an over-run as possible. The legal 
limit of moisture is 15.99 per cent. 

The incorporation of the moisture should be 
studied in relation to the following factors : 

Temperature of cream and wash water. 
Amount of cream in churn. 
Percentage of fat in cream. 
Amount of working. 
Pasteurized or raw cream. 
Degree of ripeness of cream. 
Churning butter in wash water. 
Working butter in wash water. 

The secret of moisture control lies in regulating 
the churning temperature and in adjusting the 



24 A Handbook for Dairymen 

working process according to the firmness of the 
butter as determined by the chemical, physical and 
mechanical properties of the butter fat, and in the 
constant use of a reliable moisture test. This shows 
the vital relation of temperature to over-run. In 
many plants the cost of manufacture, marketing and 
profits must come from the over-run because the 
fat is paid for at the same price per pound as the 
butter. 

As a large percentage of butter is made during 
the short season when there is a large production 
of milk, it has to be held to supply the demand 
during the rest of the year. Quality is maintained 
by storing the butter in very cold refrigerators — 
0° F. or below. If the quality of the butter is to 
be maintained, the temperature of the refrigerator 
must not fluctuate. The refrigerator should be 
equipped with a recording thermometer with the re- 
cording element located on the outside. This saves 
opening the door to observe the temperature, and 
also gives a record of the temperature. It is es- 
pecially desirable if butter is stored for some one 
else. Then, if it deteriorates in storage, the oper- 
ator can produce his records of the temperature, 
which at once show whether the deterioration is due 
to temperature or to some other cause. The value 
of such an installation was pointed out in Chapter I. 

Whey Butter. 

Whey, or the liquid portion of the milk left after 
cheese making, contains a small amount of fat. The 
amount varies with the variety of cheese made, 
usually from .8 to .3 per cent. Special separators 
have been devised to separate this fat from the whey. 
Cream rich in fat (60 to 75 per cent) is desirable. 



Butter Making 25 



This cream should be reduced with milk to the cor- 
rect percentage for churning. It may be made into 
butter the same as any cream. It is best to pasteur- 
ize it and add a larger percentage of starter. Be- 
cause the whey naturally contains the softer fats, 
whey butter is apt to be soft-bodied. For this 
reason, it should be churned at as low a temperature 
as possible. If the milk from which the whey is 
obtained was of good quality, the cream separated 
as soon as the whey was drawn and the directions 
above followed, whey butter should be of good 
quality. 



CHAPTER IV 

MILK AND CREAM 

It has been estimated that the total annual produc- 
tion of milk in the United States is valued at 
approximately two billion dollars. Of this huge 
amount 45.7 per cent is consumed as fluid or whole 
milk. In brief, these figures show the tremendous 
importance of this one branch of the dairy industry. 

Market milk not only is of importance from the 
standpoint of its production value, but it has be- 
come a vital factor in the life and well-being of 
every community. Boards of Health in a great 
many localities enforce stringent regulations in re- 
gard to the source of the milk supply and the 
pasteurization of the milk. But progressive dairy- 
men exercise greater care than is even prescribed by 
the Boards of Health. 

In the last analysis the successful handling of 
market milk depends upon the careful regulation of 
temperature. The growth of bacteria, pasteuriza- 
tion, storage and the efficient operation of the plant 
are all influenced by temperature. The dairyman 
knows that temperature influences these processes, 
but is that knowledge accurate and is it used to 
make his business more profitable? As one superin- 
tendent of a large Boston dairy said: "Until I kept 
a record of temperatures, a careless employee, in the 
Pasteurizing Department alone, could waste his 
wages in steam and water several times a day." 

Pre-H eating and Clarifying. 

As the milk is delivered to the dairy at a lower 
temperature than is required for proper handling 



Milk and Cream 



27 




View of the pre-heater and clarifier at the Turner Centre 
System, Somerville, Mass. The Foxboro Long Distance 
Dial Type Indicating Thermometer inserted is commonly 
used on pre-heaters. 



(often 40° F, in winter time) a pre-heater is usually 
necessary. The heating may be accomplished by 
running the cold milk counter-current to hot water, 
or by other methods. A temperature of 85° to 
100° F. has proved satisfactory for the subsequent 
process of clarifying. It is almost necessary to in- 
stall a recording thermometer on the pre-heater in 
order to save heat and to prevent the milk from 
scorching. 

The centrifugal clarifier strains the milk at any 
temperature, but works more efficiently when the 
milk is heated 85° to 100° F. The clarifier removes 
the dirt, pus cells, blood corpuscles, etc., without 
separating the whole milk and aerates the milk, 
which improves its flavor. The machine may be belt 
or turbine driven, and if the latter a pressure reg- 
ulator in the steam line will insure a uniform pres- 
sure. The clarifier will not operate efficiently unless 
it is run at the prescribed speed. 



28 



A Handbook for Dairymen 



Pasteurization. 

There are two general methods of pasteurization, 
— the Holding and the Flash methods. A more 
recent development is the pasteurization of the milk 
after it has been bottled. However, this method is 
not used so generally as the first two. 

The Flash Method: The milk or cream is heated 
to a temperature of 170° to 180° F. for an instant, 
and then cooled. Unless great care is exercised the 
high temperature is likely to impart a cooked flavor 
to the product. 

The Holding Method: The milk is heated to a 
temperature of 142° to 145° F. and held at this 
temperature for thirty minutes. 

Bottle Method : 
After the milk is 
packaged, it is placed in a large 
container and heated by live 
steam. Although the application 
is different, the principle of pas- 
teurization is the same as has been 
described above. The bottles are 
cooled by running cold water into 
the container. It is claimed that 
this method of pasteurization is 
more efficient because there is little 
or no chance for the milk to be 
contaminated. 

Pasteurization is the critical 
stage in the handling of market 
milk. Temperatures in the pas- 
teurizer should be known and care- 
fully regulated at all times. Even the most experi- 
enced operator cannot be so efficient or so vigilant 
as a recording thermometer or a temperature con- 




Special Foxboro 
bulb and fitting for 
the Bottle Method 
of Pasteurizing. 



Milk and Cream 



29 




Installation of Foxljoro Uccurding Thermometers on Burrell 
continuous pasteurizer at the Turner Centre System, Somer- 
ville, Mass. The arrows indicate the location of the ther- 
mometer bulbs. 



troller-recorder. The only way a superintendent can 
check the efficiency of his plant is to keep a record 
of the operations involving temperature. The regu- 
lations set down by most Boards of Health require 
that a record be kept each day showing the tempera- 
ture at which the cream or milk is heated and the 
time it was held at this temperature. 

Three thousand dollars were saved the first year 
by one medium-sized dairy after four recording 
thermometers and two temperature controllers were 
installed in the Pasteurizing Department. The in- 
stallation paid for itself during the first two weeks 
of operation. 

Cooling 

After pasteurization, the milk should be cooled 
rapidly with as little contamination as possible, to a 



30 A Handbook for Dairymen 




Installation of Foxboro Recording Thermometers on coolers 
at the Turner Centre System, Somerville, Mass. Arrows show 
where thermometer bulbs are connected to the coolers. 



temperature of about 40° F. At this temperature 
the growth of any organisms which may have sur- 
vived pasteurization is very slow. The ease of clean- 
ing the cooling device should not be overlooked. 
The milk may be cooled by running it counter-cur- 
rent to cold water, or by other equally effective 
methods. A recording thermometer should be used 
as a check on the efficiency of the cooler. 

The milk is often held in large glass-lined holding 
tanks until it can be packaged. The tanks are 
equipped with brine pipes for cooling and an agitator 
to keep the cream evenly distributed throughout the 
milk. The operator will find a recording ther- 
mometer a great aid in maintaining a uniform cool 
temperature in the tanks. If the milk or cream 
warms up, it is very likely to sour. 

As it is customary to prepare the milk and cream 



Milk and Cream 31 



one day and to deliver it the next, it is necessary to 
refrigerate the milk for several hours. The refrig- 
erator temperature should be held uniformly at 
40° F. and the milk should not be allowed to freeze. 
Here, too, the only practical precaution for the 
dairyman is a recording thermometer. With the 
recording elements on the outside of the refrigerator, 
the temperature may be observed and maintained 
uniformly without the loss otherwise incurred by 
frequent opening of the door for temperature 
observation. 

Standardizing Milk and Cream. 

To satisfy the consumer, cream or milk containing 
the same percentage of fat should be sold every day. 
Because a separator will not deliver cream testing 
the same percentage of fat every day the cream must 
be standardized. 

Standardizing milk or cream consists of raising 
or lowering the fat content to a fixed standard. 

In standardization, there are two classes of prob- 
lems involved: first, a certain fixed amount of milk 
is to be made up or a certain amount of standardized 
milk is desired. Second, a certain amount of milk or 
cream is to be used and enough of another product 
added to make the mixture test a certain percentage 
of fat. In the latter case the amount of the mixture 
is indefinite. 

The original method of computing problems in 
standardization is long and difficult, but a scheme 
has been devised that is simple. The method is as 
follows : 

Draw a rectangle and place in the center of it the 
percentage of fat desired. Place at the left-hand 
corners of the rectangle the percentage of fat in 



J2 



A Handbook for Dairymen 



the materials to be mixed. Subtract the number in 
the center from the larger number at the left of the 
rectangle. Place the remainder on the diagonally 
opposite right-hand corner of the rectangle. Sub- 
tract the smaller number on the left-hand corner 
from the number in the center and place the re- 
mainder on the diagonally opposite right-hand 
corner of the rectangle. 

The two numbers on the right-hand corners of the 
rectangle represent the number of pounds of ma- 
terial required. If these two numbers are added, 
they will express the number of pounds of the mix- 
ture, which will contain a percentage of fat expressed 
by the number in the center of the rectangle. In 
each case the number on the right-hand corner cor- 
responds in fat test to the number on the left-hand 
corner directly opposite. 

Problem. 

How many pounds of 40 per cent cream and 3 per 
cent milk must be mixed to make milk testing 5 per 
cent.'' Using the diagram as described, the following 
result is obtained: 




This means that if 2 pounds of 40 per cent cream 
are mixed with 35 pounds of 3 per cent milk, tlie re- 



Milk and Cream 



33 



suit will be a 37-pound mixture testing 5 per cent. — 
Answer. 

Problem. 

How many pounds of 28 per cent cream and 3 
per cent milk will be required to make 500 pounds 
of a mixture testing 4 per cent? In this problem a 
definite number of pounds of the mixture is required. 




According to the diagram, 1 pound of 28 per cent 
cream is required to every 24 pounds of 3 per cent 
milk to make a mixture testing 4> per cent. This 
would make 25 pounds of the mixture, but 500 
pounds is the amount desired. In other words, the 
number of pounds desired is 20 times larger than 
the number of pounds on hand (500-^25 = 20). 
The amounts must be kept in the proportion of 1 :24. 
Therefore, in order to get 500 pounds of mixture, it 
is necessary to multiply both the 1 and the 24 by 20. 
This would give a result of 20 pounds of 28 per cent 
cream and 480 pounds of 3 per cent milk, which 
mixed will equal 500 pounds of 4 per cent milk. — 
Answer. 



34 A Handbook for Dairymen 

This problem may also be worked by simple pro- 
portion : 

1 : 25 : : X : 500 

25x = 1 X 500 

25x = 500 

X = 20, number of pounds of 28 per cent 

cream there will be in the 500-pound mixture. 

— Answer. 

If there are 20 pounds of 28 per cent cream in the 
500-pound mixture, the remainder will necessarily 
be 3 per cent milk. 

Therefore, 500 — 20 = 480, number of pounds 
of 3 per cent milk. — Ansmer. 

The number of pounds of 3 per cent milk can be 
found directly by simple proportion: 

24 : 25 : : X : 500 

25x = 24 X 500 = 12,000 

X = 480, number of pounds of 3 per cent 

milk. — Answer. 

Proof. 

In working problems in standardization, it is al- 
ways wise to prove the answer and check for mis- 
takes. According to the conditions of the problem, 
there would be 500 pounds of 4 per cent milk. This 
amount of milk would contain 20 pounds of fat 
(500 X .04 = 20). According to the results the 
480 pounds of 3 per cent milk would contain 14.4 
pounds of fat (480 X .03 = 14.4). The 20 pounds 
of 28 per cent cream would contain 5.6 pounds of 
fat (20 X .28 = 5:6). 

14.4 + 5.6 = 20 

Since the 500 pounds contain 20 pounds of fat 
and the materials of which the 500 pounds is made 



Milk and Cream 



35 



up furnish the 20 pounds of fat, the answer is 
correct. 

Problem. 

How many pounds of 3 per cent milk must be 
mixed with 150 pounds of 28 per cent cream to 
make a mixture testing 4 per cent? In this problem 
the number of pounds to be made up is not definitely 
known. 




Foxboro Automatic Temperature Recorder-Controller in- 
stalled on a flash pasteurizer at Schlosser Bros. Creamery, 
Plymouth, Indiana. This one instrument does the work of 
both controller and recorder. The chart shown is a facsimile 
of an actual chart from this instrument. The heavy lines 
show how close the temperature was held within the allow- 
able limits. The momentary high and low temperatures 
were caused by the cream supply being changed from one 
fore-warmer to another. 



36 A Handbook for Dairymen 

Working the problem by the rectangle method 
(see page 32), 1 part of 28 per cent cream is re- 
quired for 24) parts of 3 per cent milk. According 
to the terms of the problems, 150 pounds of 28 per 
cent cream must be used, and the 3 per cent milk 
must be increased 150 times. This would give 150 
pounds of 28 per cent cream (IX 150), and 3600 
pounds of 3 per cent (150X24=3600), making 
in all 3750 pounds (150 + 3600 = 3750) of a 4 per 
cent mixture. 

This problem may also be worked by simple pro- 
portion : 

24 : 1 : : X : 150 

X = 3600, the number of pounds of 3 per 

cent milk required. 

Proof. 

The 3750 pounds of 4 per cent milk will contain 
150 pounds of fat (3750 X .04 = 150). If the 150 
pounds of 28 per cent cream and 3600 pounds of 
3 per cent milk furnished 150 pounds of fat, the 
problem is correct. 

3600 X .03 = 108, number of pounds of fat 
in milk. 

150 X .28 = 42, number of pounds of fat in 
cream. 

108 -|- 42 = 150, number of pounds of fat in 
mixture. — Answer. 



Milk and Cream 



37 



Specific Gravity and Weight of Milk and Cream 
at a Temperature of 68° F. 





Per cent of fat 


Specific 
gravity 


Weight of 
one gallon 
in pounds 


Skim 


.025 

3 

3.5 

4 

5 

6 

10 
15 
18 
20 
22 
25 
28 
30 
32 
35 
38 
40 


1.037 
1.034 
1.033 
1.032 
1.031 
1.030 
1.025 
1.018 
1.015 
1.013 
1.011 
1.008 
1.006 
1.004 
1.002 
.999 
.997 
.995 


8.6295 


Milk 


8.6045 


Milk 


8.5962 


Milk 


8.5879 


Milk 


8.5796 


Milk 


8.571S 


Mixed Milk, Cream . . . 
Mixed Milk, Cream . . . 
Cream 


8.5297 
8.4714 
8.4564 


Cream 


8.4298 


Cream 


8.4132 


Cream 


8.3882 


Cream 


8.3715 


Cream 


8.3549 




8.3383 


Cream 


8.3133 


Cream 


8.2966 


Cream 


8.2800 







CHAPTER V 

ICE CREAM 

No milk product varies so much in quality as ice 
cream. This is largely due to the fact that the 
federal standard which requires that a vanilla mix- 
ture contain 14 per cent of fat and a fruit or nut 
mixture 12 per cent is not enforced. In many 
states ice cream may be sold either very low or very 
high both in fat and in milk solids not fat depend- 
ing upon the amount the manufacturer wishes to 
spend for materials. Many concerns make an ice 
cream containing 8 to 10 per cent of fat and 
30 to 35 per cent of total solids. 

The common milk products used in ice cream are 
cream, whole milk, skimmed milk, whole or skimmed 
condensed milk, whole or skimmed powdered milk and 
butter. 

The Importance of Refrigeration. 

One of the most essential parts of an ice-cream 
plant is its refrigerator. Because the demand for 
ice cream fluctuates with weather conditions, manu- 
facturers must carry a sufficient amount of raw 
materials to meet any emergency. These raw prod- 
ucts should be kept in a refrigerator at a uniform 
temperature and as near freezing as possible — but 
not frozen. Without such a refrigerator manufac- 
turers either run short of raw materials and cannot 
supply a sudden demand that would mean a large 
increase in profits, or certain of the raw products 
spoil before they are manufactured. Sour ice cream 



40 A Handbook for Dairymen 

is more often due to faulty refrigeration of raw 
materials than to anything else. 

Many ice-cream plants have a fruit storage room. 
This is similar to the storage for raw-milk products 
and in many cases is a small refrigerator partitioned 
off from the larger one. Fruits should never be 
allowed to freeze. 

Pasteurization of Milk Products. 

Some manufacturers pasteurize their milk prod- 
ucts while others do not — there is no uniform 
practice. It is a known fact that pasteurization 
reduces the viscosity, so that after being pasteur- 
ized the product must be held for some time to 
regain its viscosity. As will be pointed out later, 
the viscosity is very important in relation to swell. 
Products should be pasteurized at as low a tempera- 
ture as possible, not above 145° F., to prevent a 
cooked flavor. Any of the milk or cream pasteur- 
izers may be used. 

Basic Recipes for Ice Cream. 

Here are two basic recipes which make ten gallons 
of ice cream : 

No. 1. Without condensed milk. 
40 lbs. cream. 4 oz. gelatine in 4 lbs. water. 

8 lbs. sugar. Flavoring. 

The percentage of fat in the cream governs the 
percentage of fat in the ice cream. 

No. 2. With condensed milk. 
30 lbs. cream. 4 oz. gelatine in 

10 lbs. condensed milk. 4 lbs. of water. 

7 lbs. sugar. Flavoring. 

Either whole or skimmed condensed milk may be 
used. Plain condensed is preferable to sweetened 



Ice Cream 41 

condensed milk. Again, the percentage of fat in the 
cream may be varied to give the ice cream the de- 
sired percentage of fat. 

For standardization see page 31. The percen- 
tage of fat in the mix is figured by dividing the total 
pounds of fat by the total weight of the materials 
in the mix. (The " mix " is the unfrozen ice cream.) 

Milk powder is either used to make milk or to 
bring up the percentage of milk solids not fats or 
in place of the condensed milk, or the cream or milk 
may be made by mixing the various milk products 
mentioned above. 

Machines for Mixing Materials. 

The mixing process can be accomplished by two 
types of machines. One is the type in which the 
materials are forced through very small holes or 
slots by centrifugal force. It is known as an emulsi- 
fier. The other, in which the material is forced be- 
tween a valve and its seat by a piston pump, or 
through a very small opening between porcelain 
discs by a piston pump, is known as a viscolizer and 
homogenizer. Viscolizers and homogenizers are 
much more powerful than the emulsifiers and break 
up the fat globules so finely that the cream can 
never be rechurned. Many ice-cream makers run the 
whole mix through these machines, which increases 
the viscosity which in turn increases the swell. 

Mixing. 

Opinions differ as to the correct temperature at 
which the materials should be emulsified. Some 
manufacturers prefer to pasteurize and then emul- 
sify at the same temperature. A temperature of 
120° to 130° F. is satisfactory. The materials 
must be kept thoroughly mixed or else the fat 
rapidly separates and comes to the top. This mix- 



42 A Handbook for Dairymen 

ing may be accomplished by supplying the machine 
with the materials from a revolving coil or by an 
agitator in the supply tank. When butter is used, 
it should be cut into small pieces and then melted 
in the milk or water. 

Directly from the emulsifier, the material must be 
cooled as near 40° F. as possible, or the fat may 
separate. 

The preparation of materials to be viscolized or 
homogenized is the same as stated above. By means 
of an adjusting screw, the pressure under which the 
material passes through the machine can be regu- 
lated. The pressure may vary from 2000 to 3000 
pounds. The only objection to these machines is 
that inferior products can be made to appear better 
than they really are. This is especially true of but- 
ter. Homogenizers may also be used on market or 
fluid cream, causing it to appear much richer than 
it really is. 

The next step in the preparation of the mix is 
the adding of the correct amount of sugar. If an 
ice-cream powder is used it must be thoroughly mixed 
with the sugar. Gelatine is added to prevent the 
separation of water crystals that cause ice cream 
to be grainy or icy. There are several ways to 
prepare the gelatine. The following method gives 
good results : To eight quarts of cold water add one 
pound of gelatine, or in that ratio, then mix the 
gelatine and water and let it stand twenty or thirty 
minutes. In this length of time the gelatine and 
water mixture will be rather thick. It should then 
be heated in a water bath to 165°-170° F. While 
at this temperature it should be added slowly to the 
mix which is being agitated. The whole mix or 
each individual freezer can now be flavored. 



Ice Cream 



43 



Showing Properties of Solution of Salt (Siebly)* 
{Chloride of Sodium) 



Per cent Pounds salt Degrees or Weight Specific , 

of salt per gallon salometcr per gallon gravity j 

by weight , of solution ' 60° F. at39°F. at39°F..4°C. 



Freezing 
Specific point 
heat I F. 



1 


0.084 


4 


8.40 


1.007 


0.992 


30.5 


2 


0.169 


8 


8.46 


1.015 


0.984 


29.5 


2.5 


0.212 


10 


8.50 


1.019 


0.980 


28.6 


3 


0.256 


12 


8.53 


1.023 


0.976 


27.8 


3.5 


0.300 


14 


8.56 


1.026 


0.972 


27.1 


4 


0.344 


16 


8.59 


1.030 


0.968 


26.6 


5 


0.433 


20 


8.65 


1.037 


0.960 


25.2 


6 


0.523 


24 


8.72 


1.045 


0.946 


23.9 


7 


0.617 


28 


8.78 


1.053 


0.932 


22.5 


8 


0.708 


32 


8.85 


1.061 


0.919 


21.2 


9 


0.802 


' 36 


8.91 


1.068 


0.905 


19.9 


10 


0.897 


40 


8.97 


1.076 


0.892 


18.7 


12 


1.092 


48 


9.10 


1.091 


0.874 


16.0 


15 


1.389 


60 


9.26 


1.115 


0.855 


12.2 


20 


1.928 


80 


9.64 


1.155 


0.829 


6.1 


24 


2.376 


96 


9.90 


1.187 


0.795 


1.2 


25 


2.488 


100 


9.97 


1.196 


0.783 


0.5 


26 


2.610 


104 


10.04 


1.204 


0.771 


—1.1 



Properties of Solution of Chloride of Calcium {SieblyY 



Per cent 
by weight 



Specific heat 



Specific gravity 
at 60° F. 



Freezing point 
in degrees F. 



1 


0.996 


1.009 


SI 


5 


0.964 


1.043 


27.5 


10 


0.896 


1.087 


22 


15 


0.860 


1.134 


15 


20 


0.834 


1.182 


5 


25 


0.790 


1.234 


—8 



♦From Larsen & White's "Dairy Technology," by courtesy of the authors. 



Ageing the Mix. 

It is desirable, after the mix has been prepared, 
to " age " it by allowing it to stand. Ageing blends 



44 



A Handbook for Dairymen 




View of hardening room at the Turner Centre System, Somer- 
ville, Mass. It is very important that the temperature be kept 
even if quality is to be maintained. 

the flavors and increases the viscosity. It is usually 
done in large, insulated brine circulating coil tanks, 
equipped with recording thermometers. The one 
great danger of ageing is that the mix is likely 
to sour. Souring is determined entirely by tempera- 
ture. If the mix sours, it is practically a loss. It 
may be neutralized but it never makes a product of 
as high a grade. If cream is aged and sours while age- 
ing, it can be churned into butter, providing it has 
not been homogenized. For this reason many man- 
ufacturers prefer to age the cream rather than the 
whole mix. 

The temperature at which the mix enters the 
freezer is an important factor in relation to both 
quality and swell. The mix should enter the freezer 
as near 40° F. as possible. This helps to eliminate 
the danger of churning and of jDroducing an ice 
cream of greasy texture. 



Ice Cream 45 

How to Freeze Ice Cream. 

The freezer has a dasher with scrapers revolving 
in the center and a jacket around the outside in 
which cold brine is circulated. The rate of flow of 
the brine is determined by the pump, and after it is 
once regulated should be constant. The temperature 
of the brine may vary within wide ranges, though 
the best results are obtained when it is from -\-Q° 
to -f-10° F. Temperature is an extremely im- 
portant factor in connection with the making of 
ice cream. If the brine is too warm the cream will 
churn instead of freeze, and there will be chunks 
of butter in the ice cream. If the brine is too 
cold, the ice cream freezes too fast and then it is 
difficult, if not impossible, to obtain the swell. 

Care in freezing is of the utmost importance be- 
cause it affects both the quality of the ice cream and 
the swell. If the desired swell is not obtained, the 
business will be a failure. The rate or time to 
freeze depends upon the following factors : 

1. Temperature of brine. 

2. Rate of flow of brine. 

3. Temperature of materials when put into freezer. 

4. Materials in mix. 

5. Speed of the freezer. 

The first three factors show the important part 
that temperature plays in the freezing process. It 
should take from 12 to 20 minutes to freeze a 
batch of good ice cream. 

By " swell " is meant the increase in volume of 
the ice cream over the mix. This increase is due to 
the incorporation of the air. The factors affecting 
swell may be divided into two general classes : kind 
and preparation of materials used and method of 
freezing. 



46 A Handbook for Dairymen 



Certain combinations of these factors increase the 
swell, while other combinations decrease it. 
To obtain swell: 

1. Have viscous milk and cream. 

2. Age the milk and cream or mix. 

3. If pasteurized milk and cream are used, age 
until viscous. 

4. The cream and milk or whole mix should be 
homogenized or emulsified. 

5. Condensed milk in the mix aids in obtaining 
swell. 

6. The mix should contain at least 30 per cent of 
total solids. 

7. The dasher should run at the required speed. 

8. Mix should enter freezer as near 40° F. as 
possible. 

9. There should be a sufficient supply of brine from 
4-6° F. to 4-10° F. 

10. The cream should be whipped for a moderate 
time in the freezer. 

11. The mix should fill the freezer half full. 

12. It should require 12 to 20 minutes to freeze. 

13. The ice cream should not be below 27° F. when 
drawn from the freezer. 

The converse of these conditions will cause a de- 
crease in the amount of swell. 

If not enough swell is obtained in freezing, the 
ice cream will be soggy and heavy, and if too much 
swell is obtained the ice cream will be fluffy and 
inclined to be grainy. A swell of 85 to 100 per 
cent is satisfactory. 

The Hardening Process. 

When drawn from the freezer the ice cream is 
in a semi-fluid condition and must be frozen solid 
or "hardened." This is accomplished by placing 
the cans of ice cream in a cold room known as a 
hardening room or by packing them in ice and salt 
or placing them in a box of cold brine. The usual 



Ice Cream 



47 




Foxboro Recording Thermometers for recording hardening 
room temperatures at Schlosser Bros. Creamery, Plymouth, 
Indiana. In this case the recorders are located at a considerable 
distance from the hardening room, but there is no loss of ac- 
curacy. 



practice in the large plants is to have a hardening 
room with a temperature of — 20° F. This will 
harden the ice cream in twenty-four hours. In no case 
should the temperature be allowed to go above 0° F. 
A long-distance type recording thermometer shows 
the temperature of the hardening room at all times 
and saves loss of refrigeration due to the opening of 
the doors to learn the temperature. It also gives the 
engineer and the management a constant record. 
Much ice cream properly made and of good quality 
up to the time of hardening has been spoiled during 
the hardening process, due to fluctuations in the tem- 
perature. When the ice cream is allowed to melt and 
freeze in the hardening room, its body and texture is 
quickly ruined. It will become grainy and full of 
ice crystals. After being hardened the ice cream 
must be properly handled and packed in ice and salt 
for delivery. 



CHAPTER VI 

CONDENSED AND EVAPORATED MILK 

Condensed milk is milk in which the solids have 
been condensed by the removal of the water. This 
is usually accomplislicd by boiling the milk in a 
vacuum, although there are concentrators in which 
a vacuum is not used. Either skimmed milk or whole 
milk may be condensed, and may be made plain or 
may be sweetened by the addition of cane sugar. 

As a condensing plant usually receives milk much 
faster than it can be condensed it is usually placed 
in large holding .tanks. These tanks are insulated 
and often refrigerated in order to keep the milk cold 
and sweet. It is much easier to standardize the milk 
in the holding tanks than it is the condensed milk 
after it has been drawn from the pan. For method 
of standardization see page 31. 

The milk is first heated in large open copper ket- 
tles, called fore-warmers or hot wells, in order that 
cold milk will not be drawn into the vacuum pan. 
When sweetened condensed milk is made, about 16 to 
18 per cent of cane sugar is added to the milk in 
the hot well. Sweetened milk is heated to 180°- 
200° F. to dissolve the sugar, and the plain milk to 
130°-150° F. 

The boiling is done in a large copper container 
called a pan. The size is spoken of in terms of the 
diameter, i. e., a four-foot pan or a five-and-a-half- 
foot pan. 

The temperature is regulated by a steam jacket 
on the bottom and several steam coils inside the 



Condensed and Evaporated Milk 49 

pan. The temperature of the pan should be about 
130° F. with a vacuum or about 25 to 26 inches of 
mercury. 

It is desirable to have the heating surface in the 
pan as large as possible in order to make high steam 
pressure in the jacket and coils unnecessary, and in- 
sure complete condensation of the steam. Otherwise 
too high milk temperatures or waste of steam results. 
Steam gauges should be placed just after the valves 
connecting the jacket and coils with the main steam 
line. Twenty-five pounds' pressure is considered as 
high as can be safely used, and many condenseries 
operate with twelve to twenty pounds' steam pres- 
sure. Taking into consideration the ordinary water 
supply, fifteen pounds' steam pressure and twenty- 
five inches' vacuum are about the best conditions that 
can be steadily maintained. The temperature is 
about 135 degrees at this vacuum. 

The milk is drawn into tlie pan by vacuum. After 
enough has been drawn in to boil well, a constant 
stream maintains the same volume in the pan. Care 
must be exercised or the milk Avill boil over the top. 
The usual practice is to concentrate a trifle too much 
and then standardize by the addition of distilled 
water. This can only be done when the milk has 
been standardized in the holding tanks. 

It is very important for the successful operation 
of the pan that it be equipped with an accurate 
thermometer and vacuum gauge. A thermometer 
which is constructed so that the bulb may be well 
submerged in the milk is more sensitive to tempera- 
ture changes and at the same time makes it possible 
to place the indicator where it is convenient to read. 
Such a thermometer is known as a long-distance type 
thermometer. 



50 



A Handbook for Dairymen 



Boiling Points of Water at Different Vacua" 



Absolute 

pressure 

per square inch 


Vacuum inches 

of mercury 

column 


Vacuum 
millimeters of 1 
mercury- 
column 1 


Temperatures of 

boihng point of 

water, F. 


Temperatures of 

boihng point of 

water.C. 


14.720 


0.00 


00 


212.00 


100.00 


14.010 


1.42 


36 


209.55 


98.5 


13.015 


3.45 


88 


205.87 


96.8 


12.015 


5.49 


139 


201.96 


94.3 


11.020 


7.52 


191 


197.75 


91.9 


10.020 


9.56 


243 


193.22 


89.5 


9.020 


11.60 


295 


188.27 


86.75 


8.024 


13.63 


346 


182.86 


83.7 


7.024 


15.67 


398 


176.85 


80.5 


6.024 


17.70 


450 


170.06 


76.8 


5.029 


19.74 


502 


162.28 


72.5 


4.029 


21.78 


553 


153.01 


67.2 


3.034 


23.81 


605 


141.52 


60.8 


2.034 


25.85 


657 


126.15 


52.3 


1.040 


27.88 


708 


101.83 


38.7 


.980 


28.00 


712 


100.00 


37.8 


.735 


28.50 


724 


90.00 


32.2 


.544 


28.89 


734 


80.00 


26.7 


.402 


29.18 


741 


70.00 


21.1 


.294 


29.40 


747 


60.00 


15.6 


.216 


29.56 


751 


50.00 


10.0 


.162 


29.67 


754 


40.00 


4.4 


.127 


29.74 


756 


32.00 





* By courtesy of the Buffalo Foundry and Machine Company. 



Condensation. 

The vapors from the pan are condensed by a spray 
and column of water. It is desirable for the oper- 
ator to know the temperature of the water just be- 
fore and directly after going though the condenser, 
as the efficiency of the condenser can be determined 
by the temperature of the water. If the water com- 



Condensed and Evaporated Milk 51 



ing from the condenser is cold, it shows that some- 
thing is wrong. If the temperature of the condensing 
water is 55° to 65° F. the water coming from the 
condenser should be 15° to 20° colder than the tem- 
perature of the pan, or about 110° F. ; below this 
temperature there is sure to be much water wasted. 
The amount of concentration or the ratio of the 
condensed to the raw product, i. e., 1 to 3 or 1 to 
3.5, etc., is determined by the market demand. The 
amount of condensation in the pan is determined 
by sampling and testing with a special hydrometer 
calibrated in degrees Baume. Wheij the proper 
concentration is reached, the milk should be drawn 
off rapidly and cooled, unless superheated condensed 
milk is being made. Superheated condensed milk is 
made by turning live steam directly into the con- 
densed milk as soon as the proper concentration is 
reached. The temperature is raised to about 210° F. 
This high heat precipitates the albumin and gives 
the condensed milk a thick, heavy body, desired by 
many ice-cream manufacturers. 

Cooling the Milk. 

Sweetened condensed milk should be cooled gradu- 
ally. It is placed in large cans, which in turn are 
placed in tanks. The cans are revolved and station- 
ary paddles stir the milk. The water in the cooling 
tank is at first fairly warm (about 90° F.) and the 
milk is about 115° F. to 130° F. After a few 
minutes cold water is supplied until the milk has 
reached approximately 70° F. The time for this 
cooling should be about two hours in all. 

Another common practice is to place the con- 
densed milk in large tanks and cool it by pumping 
it through coils submerged in cold water or brine. 



52 A Handbook for Dairymen 

Too rapid cooling must be guarded against in this 
process, as this causes excessive sugar crystalliza- 
tion. 

The sweetened condensed milk, containing enough 
sugar to preserve it, is usually put in small cans for 
household use. The plain condensed milk, however, 
spoils very rapidly unless refrigerated at a tempera- 
ture of 32° to 40° F. It should not be allowed to 
freeze. The refrigerator should be held at a uniform 
temperature, otherwise spoilage is more rapid. Plain 
condensed milk is used largely by ice-cream and 
candy manufacturers and bakers. Because the de- 
mand for plain condensed is not steady, it is often 
necessary to hold it for a considerable period. 
This can be done if the directions above are followed. 

Evaporated Milk Processing and Sterilizing. 

Evaporated milk is the term applied to sterilized, 
plain condensed milk. It is made the same as plain 
condensed but it is not concentrated quite so much; 
usually the ratio is one to two or one to two and a 
half. The milk is standardized in the holding tanks 
and the finished product is standardized by the ad- 
dition of distilled water. The condensed milk is 
superheated, otherwise the later heating while ster- 
ilizing would give a tough curd. After superheat- 
ing, the milk is homogenized, which breaks up the 
milk particles. It is then usually run into holding 
- tanks until it can be packaged. 

The package milk is sterilized to prevent it from 
spoiling. The sealed cans are placed in the rack 
of a large cast-iron sterilizer heated with steam. 
The time and temperature may be varied to suit 
conditions, but the milk should not be heated above 
235° F. The cans are revolved in the sterilizer to 
give uniform heating and to break up the curd. 



Condensed and Evaporated Milk 53 

The sterilizer is equipped with steam and vacuum 
gauges and automatic temperature controller and 
temperature recorder. The cans are cooled either by 
running cold water into the sterilizer or by immers- 
ing the cans in cold water. They should be cooled in 
15 to 20 minutes to a temperature of 70° to 80° F. 
They are then placed in a shaker which shakes 
out the curd which is formed because of the high 
temperature. The cans are incubated for 20 to 30 
days at a temperature of 75° to 85°. Defective cans 
will swell and bulge. 

Federal Requirements. 

The federal standards for condensed and evapo- 
rated milk are as follows : " Sweetened condensed 
milk, sweetened evaporated, sweetened concentrated 
milk, is the product resulting from the evaporation 
of a considerable portion of the water from the 
whole, fresh, clean lacteal secretion obtained by the 
complete milking of one or more healthy cows, 
properly fed and kept, excluding that obtained within 
fifteen days before and ten days after calving, to 
which sugar (sucrose) has been added. It contains, 
all the tolerances being allowed for, not less than 
twenty-eight (28) per cent of total milk solids and 
not less than eight (8) per cent of milk fat. 

" Unsweetened condensed milk, evaporated milk, 
concentrated milk, is the product resulting from the 
evaporation of a considerable portion of the water 
from the whole, fresh, clean lacteal secretion ob- 
tained by the milking of one or more healthy cows, 
properly fed and kept, excluding that obtained 
within fifteen days before and ten days after calving, 
and contains, all tolerances being allowed for, not 
less than twenty-five and five-tenths (25.5) per 



54 A Handbook for Dairymen 

cent of the total solids and not less than seven and 
eight tenths (7.8) per cent of milk fat. 

" Sweetened condensed skimmed milk, sweetened 
evaporated skimmed milk, sweetened concentrated 
skimmed milk is the product resulting from the 
evaporation of a considerable portion of the water 
from skimmed milk to which sugar (sucrose) has 
been added. It contains, all tolerances being allowed 
for, not less than twenty-eight (28) per cent of 
milk solids. 

" Unsweetened condensed skimmed milk, evapo- 
rated skimmed milk, concentrated skimmed milk, is 
the product resulting from the evaporation of a con- 
siderable portion of the water from skimmed milk, 
and contains, all tolerances being allowed for, not 
less than twenty (20) per cent of milk solids." 

Continuous Evaporators. 

Continuous evaporators evaporate the water from 
the milk by heating the milk at atmospheric pressure. 
No vacuum is used. With one type of machine the 
milk is pre-heated and then delivered inside a hollow 
copper drum. In this drum is a revolving dasher 
with blades, similar to an ice-cream freezer. Out- 
side the drum is an insulated jacket. Into the small 
space between the drum and jacket live steam is ad- 
mitted with 40 to 60 pounds' pressure. This heats 
the milk and evaporates the water. Scrapers remove 
the milk from the jacket and so keep it from burning. 
Any desired concentration may be secured. After 
being condensed the milk must be cooled. There is 
a continuous flow of milk into the machine and of 
condensed milk away from the machine. 

Another type of condensing evaporator is some- 
what similar, except that air is blown through the 



Condensed and Evaporated Milk 55 

hot milk, assisting in the evaporation, and also re- 
moving bad odors from the milk. 

Condensed Buttermilk. 

Condensed buttermilk is used largely for stock 
and poultry foods. It should be sour and may be 
condensed after any of the following methods : grav- 
ity, centrifugal separation in vacuum pan or concen- 
trator. 



CHAPTER VII 

MILK POWDER 

It is possible to reduce milk to a powder by the 
elimination of the water and, at some later date, by 
the addition of water again to turn the powder back 
to milk. This powder is now commonly made in this 
country after two different processes. One, the hot- 
roll or film-drying process, and the other the spray 
process. 

The hot-roll or film-drying processes in common 
use are the Hatmaker and Ekenberg. Others are 
Parsburg, Gathsmaun, Just and Buflovak. 

The spray processes are the Merrell-Soule and 
Gray processes. Many of the processes and the 
necessary apparatus are covered by patents, so that 
manufacturers who use them are often obliged to 
pay a royalty. 

Description of Standard Processes. 

The essential equipment required for the Hat- 
maker process consists of two horizontal, hollow, 
steam-heated, revolving metal cylinders. These 
cylinders are installed sufficiently close to each other 
so that all the milk comes in contact with the cylin- 
ders. The surface of these cylinders is heated to 
212° F. and below 270° F. The high temperature 
reduces the solubility of the finished powder. The 
patent claims that the treating of the milk with 
calcium chloride or with the double salt of sodium 
and calcium citrate, to reduce the acidity of the 
milk, and with alkaline hypochlorite to preserve the 
fatty acids in the finished product, causes the milk 



Milk Powder 57 



powder to be more soluble. The milk is delivered 
into the rolls from a distributing tank with an ad- 
justable discharge. This tank is placed in the center 
over and between the two rollers. The film of dried 
milk is removed from the rolls by means of scrapers 
and falls into receptacles. It has then to be placed 
on porous racks in a dry kiln in order to dry it com- 
pletely before it is ground. 

The Ekenberg process is a film drier operating 
in a partial vacuum. The machine which does the 
drying is called an exsiccator. It consists of a re- 
volving steam-heated drum inclosed in a vacuum 
chamber. The temperature of drying varies with 
the steam pressure in the drum. It is claimed that 
the drying takes place at a temperature of 100° to 
120° F. The fact that the milk is dried in a vacuum 
makes it possible to do it at a low temperature. The 
milk is first partially condensed by being brought in 
contact with the concave ends of the rolls. It is 
then sprayed on the rolls and dried milk is removed 
by a scraper. Next it falls into a receptacle. This 
receptacle may be removed when full by means of a 
special arrangement without breaking the vacuum 
about the roll. 

The films of milk are placed on screen racks and 
put in a dry kiln and held at a temperature of 90° F. 
When completely dried the milk is ground and 
packaged. It may be packed in various sized tin or 
wood boxes or barrels. 

The Merrell-Soule is a spray process of drying. 
The milk is first partly condensed in an ordinary 
vacuum pan. Then by means of a pressure pump 
it is forced into the drying chamber in the form of a 
fine spray or mist. Air is filtered and blown over 
radiators in an air-heating chamber and then into 
the drying chamber. This dry hot air meets the 



58 A Handbook for Dairyynen 

spray of milk and takes up the moisture. The milk 
falls on the floor of the drying chamber as milk 
powder and the moisture-laden air escapes from the 
drying chamber. 

The Gray is also a spray process of drying. This 
process is covered by several patents and several 
different desiccating arrangements have been used. 

Definition of Milk Powder. 

The federal standards of milk powder are as fol- 
lows : " Dried milk is the product resulting from the 
removal of water from milk, and contains, all toler- 
ances being allowed for, not less than twenty-six 
per cent (26.0%) of milk fat and not more than five 
per cent (5.0%) of moisture. 

" Dried skimmed milk is the product resulting 
from the removal of water from skimmed milk and 
contains, all tolerances being allowed for, not more 
than five per cent (5.0%) of moisture." 

Much of the milk powder made in this country is 
used in the warm states, where it is difficult to pro- 
duce milk. Considerable quantities are exported to 
tropical countries. Many ice-cream plants use it 
to standardize the mix. Bakers also use it. 



CHAPTER VIII 

CHEESE 

Undoubtedly less is known about cheese making 
than any other dairy manufacturing process. This 
is probably due to the following facts : the many 
varieties of cheese, the diversity of the process of 
manufacture and the complex organic changes which 
take place during cheese ripening. It is claimed by 
some authorities that there are 700 known varieties 
of cheese. The process of manufacture and curing 
is different for each one. 

There are certain varieties which are more ex- 
tensively made than others. With these, it is known 
that if certain operations are performed at a definite 
time in a particular way that a definite result will 
follow. But the reason is not known. Cheese may 
be made from whole milk, skimmed milk or partially 
skimmed milk. 

The varieties of cheese commonly made from full 
skimmed milk are cottage, hoop, pressed, bakers, pot 
and kosher. Any of the other varieties may be made 
from either whole milk or partially skimmed milk, 
although most of them are made from whole milk. 

Cheese may be classified in several ways : according 
to the amount of moisture it contains, the country 
in which it is made (each country is more or less 
famous for some special variety of cheese), and the 
combination of the texture and the method of 
ripening. 

Classification of these according to the amount 
of moisture it contains : 



60 A Handbook for Dairymen 

I. Soft cheese containing 45 to 75 per cent water. 
They are Cottage Cheese, Pot Cheese, Hoop Cheese, 
Neufchatel Cheese, Cream Cheese, Pimento Cheese 
and Gervais Cheese. 

II. Soft cheese, ripened, containing from 40 to 50 
per cent water, include Camembert, Brie, d'Isigning, 
Leiderkranz and Limberger. 

III. Hard cheese, containing 30 to 45 per cent 
water are Edam, Gouda, Cheddar, Brick, Gorgon- 
zola, Swiss, Parmesan and Roquefort. 

Classification of cheese according to countries in 
which they originated, or in which they are commonly 
and extensively made : 

United States American Cheddar 

p T 1 ( English Cheddar 

"^ ^" I Stilton 

France i Camembert 

\ Roquefort 
Switzerland ; Swiss 

Holland / Edam 

\ Gouda 

Italy I Gorgonzol 



a 
Parmesan 



Other countries make a characteristic cheese of 
their own, but these forms are not commonly known 
in this country. 

Classification according to the method of ripening 
and the texture: 

''Cheddar — Close texture 
Swiss — Large shiny holes 
Parmesan — Small holes 
Hard Cheese J Gorgonzola — Ripened by mold, blue 
All ripened | veined 

Stilton — Ripened by mold, blue veined 
Edam — Close texture 
^ Gouda — Close texture 



Cheese 



61 



Soft Cheese 



'Cottage 

1. Not ripened, eaten J Cream 

fresh ) Neufchatel 

^and the like 

2. Ripened by molds 

(A) Outside the cheese, Camembert 

(B) Inside the cheese, Roquefort 

3. Ripened by bacteria alone 

Limberger 
Munster 



What is usually termed cheese making may be 
divided into two parts: one the making of the curd 
or green cheese, and the other the ripening or de- 
veloping of the cheese's characteristics, especially 
the flavor, body and texture. 

The making consists of coagulating the solids in 
the milk, developing the desired amount of acid, and 
the elimination of the water or whey. When first 
made, the green curd or cheese is tough, rubbery and 
tasteless. Due to the changes which take place dur- 
ing the curing, the flavor develops and the body and 
texture change. 

In order to secure a cheese of the best quality, 
the curd must be properly made and then cured. 
The process of making any cheese consists of the fol- 
lowing operations, which may be varied for each 
variety of cheese. 

For some varieties, such as Swiss and Limberger, 
it is not necessary to ripen the milk, because the 
cheese is made from sweet milk. INIilk is usually 
ripened by the addition of starter. The temperature 
at which the rennet is added and the temperature to 
which the curd is heated varies with the different 
cheeses, shown in the following table : 



62 



A Handbook for Dairymen 



Variety of Cheese 


Temperature Rennet added 


Temperature Curd is Cooked 


Cheddar 


84° 


to 96° 


F. 


98° to 100° F. 


Swiss 


92° 


to 96° 


F. 


128° to 135° F. 


Limberger 


90° 


to 96° 


F. 


96° to 98° F. 


Camembert 


84° 


to 86° 


F. 


Not cooked 


Roquefort 


82° 


to 84° 


F. 


Not cooked 


Edam 


85° 


to 88° 


F. 


93° to 96° F. 


Neufchatel 


72° 


F. 




Not cooked 


Cream 


72° 


F. 




Not cooked 


Munster 


84° 


to 86° 


F. 


98° to 108° F. 


Brick 


92° 


to 96° 


F. 


110° to 115° F. 



The amount of rennet varies from 2 to 6 ounces 
per thousand pounds of milk, depending upon the 
varieties of cheese, the kind of curd desired, and the 
temperature at which the rennet is added. The 
length of time of coagulation depends upon the kind 
of curd desired, and the succeeding operations. 
Sometimes the curd is cut very soft, and sometimes 
it is allowed to coagulate very slowly, taking several 
hours or overnight. 

The curd may be either cut or broken. It is 
usually broken when the coagulated curd is put 
directly into the draining forms, as in the making of 
Camembert, Neufchatel and the like. The size of 
the pieces into which the curd particles are cut de- 
pends upon the rapidity of firming and the dryness 
desired. The time to remove the whey varies with 
each kind of cheese. Some varieties may be placed, 
without heating or cutting, into the draining molds 
and allowed to drain. A good example of this is 
Camembert and Neufchatel. With the other varie- 
ties it may be necessary to cut the curd, heat it and 
allow time for the whey to be expelled or for the 
curd to become firm. This may take one to three 
hours from the time of coagulation before it is time 
to remove the whey. 

Some varieties of cheese, such as Cheddar, are 



Cheese 



63 



salted while the curd is yet in the vat and before it 
is put to press. Other varieties are salted from the 
outside after the cheese is entirely formed. This is 
done by rubbing dry salt on the cheese or soaking 
the cheese in a very salty brine. Many varieties of 
cheese do not have to be pressed, for the curd will 
naturally settle together, but with other varieties 
the curd must be subjected to very heavy pressure 
to make it go together. 

Many cheeses which have been properly made are 
ruined by improper methods of ripening. On the 
other hand, no defects of manufacture can be 
remedied during the ripening process. 

Authorities disagree as to 
what causes cheese ripening, 
but it probably is due to 
a combination of factors, 
namely, humidity, tempera- 
ture, micro-organisms, en- 
zymes and chemical agents. 
In the country where the 
cheese originated, the ripen- 
ing is a natural process and 
does not need any special 
attention. In a country 
where the factors of humid- 
ity and temperature are dif- 
ferent, it is necessary to 
try to duplicate the proper 
climate conditions. To do 
this, humidity and tempera- 
ture recorders should be 
installed in the curing rooms. 
Thus, both humidity and tem- 
perature can be accurately 
judged and a record kept. 




Foxboro Recording 
Psychrometer for recording 
the room temperature and 
the wet bulb temperature, 
thus giving a constant rec- 
ord of humidity. Recorder 
may be placed outside of 
the area in which humidity 
is controlled. 



64 A Handbook for Dairymen 

While in the curing room cheese must have con- 
stant attention. It must be turned and kept free 
from mold. Some varieties, such ns Limbcrger, 
Munster and Swiss, must be rubbed to develop a 
rind. 

If allowed fully to cure or ripen, the commercial 
life of the cheese is very short. So it is the practice 
to ripen the cheese partially when packaged and put 
on the market. The time of packaging and market- 
ing is so arranged that by the time the consumers 
receive the cheese, it is fully ripe or cured and ready 
for consumption. 

Certain varieties of cheese, such as Cheddar and 
Swiss, are made extensively during the summer when 
milk is abundant. These cheeses are then put in 
storage, after being partially cured. The cheese 
should be held as near freezing and with as little 
fluctuation in temperature as possible. There should 
be a continuous record of the temperature changes. 
The storage should be dry, so that the cheese will 
not mold. Some varieties of cheese, especially Ched- 
dar, when partially cured so that they have a firm, 
dry, smooth rind, are dipped in hot paraffine. This 
coat of paraffine prevents the evaporation of the 
moisture, and tends to prevent the entrance of mold. 
The paraffine is heated to 180° F. and the cheese 
held in it four to six seconds. If the paraffine is too 
cold or the cheese is damp the paraffine will not stick. 



CHAPTER IX 

CASEIN AND MILK SUGAR 

The making of commercial casein is a very simple 
process, but one which requires strict observance of 
temperature. Skimmed milk is heated to a tempera- 
ture of 86^^ to 90 F., and the casein is precipitated 
by the addition of sulphuric acid. Hydrochloric 
acid and rennet are also used. The acid should be 
diluted by pouring it into cold water. Never pour 
the water into the acid. Just enough acid should be 
used to get a clear whey, which shows that all the 
casein has been precipitated. If too much acid is 
used, it will cut the casein, causing it to be grainy 
and chunky. As soon as it is coagulated, the curd 
should be broken up and the whey drawn off. The 
curd should then be thoroughly washed and worked 
in water that is at least 180° F. The washing re- 
moves the acid and the working causes the casein to 
unite. After being worked, the curd will draw out 
like taffy candy. If too much acid is used, it will 
not draw out. 

Casein may be precipitated as when making cot- 
tage or pot cheese. It is then necessary to press 
this curd to remove the whey, after which it is ground 
and dried. It is claimed, however, that this method 
does not give a good grade of casein. 

In this condition, the casein is known as green 
casein or green curd. It contains considerable mois- 
ture and will spoil in a short time. It may be dried 
in the same plant where made, or shipped to jobbers 
who have drying plants. 

The drying is usually done by grinding the green 
curd and spreading it in thin layers on screen racks. 



66 A Handbook for Dairymen 

These racks are placed in a dry kiln and the casein 
dried for twenty-four hours. The heat for drying 
is obtained by blowing air over hot radiators. The 
temperature of the kiln should not be above 115° F. 
The fan and ventilators are usually connected with 
a thermostat control and the kiln with a recording 
thermometer. If the temperature rises too high, it 
discolors the casein and reduces its solubility. 
Rotary dryers and vacuum dryers are also used con- 
siderably for drying casein. 

Casein is used in the making of certain glues, 
paints, papers, textiles and prepared foods. It is 
also used for imitation ivory, horn, etc. 

Milk Sugar. 

Milk sugar is manufactured as follows : Whey, 
obtained from commercial casein plants or cheese 
factories, is acidified and heated to its boiling point 
in large vats, in order to precipitate the albumin. 
The solution is then treated with calcium hydroxide 
and evaporated in a vacuum pan until it forms a 
syrup. It is then filtered and evaporated again at 
about 100° F. to a thick syrup, which is removed, 
placed in shallow containers and cooled. After one 
or two days it has crystallized into the crude yellow 
sugar. It is then placed in a centrifugal machine 
provided with sieves and washed to remove impuri- 
ties. The washed crystals are redissolved in hot 
water and treated with chemicals. The clear liquid 
is then heated to about 170° F. and filtered through 
charcoal to remove coloring matter. It is now con- 
densed to a solid mass in a vacuum pan, which is 
washed and dried on racks in a drying room in which 
a temperature of approximately 140° F. is main- 
tained. When dry it is powdered and packed for 
shipment. 



CHAPTER X 

THE POWER PLANT 

It is not the province of this book to discuss the 
question whether a steam boiler, a gas engine, or an 
electric motor is the best equipment for the dairy 
power plant. There are operating conditions under 
which a combination of all three of these would prove 
to be the most economical in the end ; and there are 
other conditions which seem to leave little choice to 
the dairyman. The relative local cost of coal, gaso- 
line, and electricity would have to be considered very 
carefully, and the particular milk products to be 
manufactured, and a dozen other purely individual 
conditions. We content ourselves, therefore, with 
referring the dairyman interested in this important 
question to Bulletin 747 United States Department 
of Agriculture : " The Economical Use of Fuel in 
Milk Plants and Creameries," by John T. Bowen. 
In this bulletin of forty-seven pages every phase of 
the dairy power-plant problem is discussed in a 
manner that makes it extremely valuable to the 
Dairy Industry. 

Whatever be the kind of power employed, however, 
the power plant must certainly not be overlooked 
when the question of indicating and recording instru- 
ments is being considered. Everything gained in the 
way of productive efficiency and economy in the milk- 
handling rooms may easily be lost by neglect in the 
power plant. The cost of fuel alone may run higher 
than that of any other item of operating expense; 
and the waste of steam and water, of brine and 
ammonia, may more than offset the economical ad- 



68 A Handbook for Dairymen 

ministration of other departments. It cannot, there- 
fore, be overemphasized that efficiency and economy 
in the power plant are fully as important as the con- 
trol of temperature and pressure in the milk-han- 
dling rooms, and that they are just as easily attained. 

All this applies not only to large modern plants 
of complex character, but also to the small plant 
with its inadequate and, sometimes, antiquated equip- 
ment. Indeed, such small plants often offer even 
greater opportunities for improvement and economy 
through the installation of the proper instruments. 
Whether the boilers and refrigerating macliines are 
old or new, large or small, the operators should be 
provided with high-grade indicating and recording 
instruments, in order that they may have at all times 
sufficient information about conditions to maintain 
a high efficiency and to prevent the loss of costly 
heat units. 

It is assumed here that steam power and some 
system of artificial refrigeration are used. 

Now the choice of indicating and recording in- 
struments for the power plant should be determined 
by a careful consideration of kind, quantity, and 
quality. To overload a small plant with instruments 
that cannot be used to advantage is to gain nothing 
but expense; yet it is just as shortsighted to attempt 
to do without those that are really essential to estab- 
lish a high plant standard. In order to make the 
installation of instruments an investment rather 
than an expense, study the performance of the 
plant itself, note the variable conditions which affect 
efficiency, and then determine what instruments are 
needed. 

The particular instruments mentioned here are 
simply suggestive. It may be that some plants will 
not need them all, but it is very probable that even 



The Power Plant 69 



the engineer of the smallest plant will discover a few 
suggestions that will help him to reach a higher 
eflSciency and a lower cost in his department. 

For the boiler room we recommend Recording 
Pressure Gauges for steam, Recording and Indicat- 
ing Thermometers for feed-water, stack, steam, and 
economizer temperatures ; Recording and Indicating 
Draft Gauges, and a CO Recorder for flue-gas 
analysis. 

In the refrigerating room, thermometers should be 
provided for the ammonia compressors, freezing 
tanks, condenser-water, forecooler-water, liquid am- 
monia, brine lines and brine tanks. A Two-Pen 
Recording Pressure Gauge for both low and liigh 
pressure ammonia attached to the compressor will 
give a positive check on the efficiency of its operation. 

A knowledge of the temperatures of the brine 
entering and leaving the cooler is of utmost im- 
portance to a dairyman. Unless he has accurate 
and continuous information of these temperatures 
the efficiency of the plant cannot be maintained. Re- 
cording thermometers tell the whole story, and from 
a study of the charts the temperature of brine flow 
and refrigerant can be regulated. 

For the condenser-water, recording thermometers 
make it possible for the operator to estimate the 
number of gallons required per ton of refrigeration 
by recording the temperature of the water as it runs 
on the condenser and as it leaves. They give also a 
check on operating conditions. If the records show 
an increase of temperature above normal of the 
water leaving the condenser, the water pump, or 
system needs attention. If the temperature of the 
water running over the condenser shows a decrease, 
less ammonia has been delivered to the condenser. 

On the ammonia compressor, recording thermome- 



70 A Handbook for Dairymen 

ters will tell you whether there is enough ammonia 
in the line, whether it returns superheated, whether 
the cooling of the compressor — either by water 
jacket or liquid injection — is correct. By record- 
ing both the suction and discharge temperatures of 
the compressor, the operator has an accurate and 
continuous picture of what is going on while the 
plant is in operation. 

These are only a few isolated instances of what 
can be done in the refrigerating room alone by an 
intelligent use of recorders. Wherever possible in 
the boiler room and the refrigerating room, record- 
ing instruments should be installed. Their slightly 
additional cost above indicating instruments is far 
offset by the greater value gained by the continuous' 
records which the operator can compare and study. 
If properly installed and faithfully used, these in- 
struments will provide the engineer with the most 
valuable information on all the conditions upon 
which the productive efficiency and economy of the 
plant depend. 

It is worth emphasizing that, where it is a ques- 
tion of temperature, or pressure, guessing is un- 
scientific, uneconomical, and unsafe. In the power 
plant, knowledge alone is power ; not memory — that 
is too treacherous ; not scraps gathered at irregular 
intervals by glancing at an indicator — that is the 
little knowledge which is a dangerous thing. What 
is needed is complete recorded knowledge of what is 
happening all the time in and around the boiler and 
the refrigerating equipment. And this is just what 
recording instruments give. They are not only per- 
petual guides to the operators, but they give the 
engineer an opportunity to compare various records 
and thus establish an efficient operating standard. 

Finally, cheap indicating and recording instru- 



The Power Plant 71 

ments are, like most other cheap things, dear at any 
price. In the milk-handling rooms and in the power 
plant accurate knowledge of temperatures and pres- 
sures often creates just that distinction between the 
dairy product that has to be sold at a loss because 
something is not quite standard about it, and the 
product that is perfect in purity and flavor because 
the conditions essential to quality have been care- 
fully watched and controlled. Real quality instru- 
ments — high-grade, accurate, and dependable — 
very soon save many times their initial cost, and 
should never be considered as an extra expense but 
as a definite investment. Nowhere is the " Penny- 
Wise, Pound-Foolish " policy more to be avoided 
than when equipping the dairy with indicating and 
recording instruments. Get the best. 



72 



Dairy Instruments 




Some Foxboro Dairy Instruments 



Dairy Instruments 73 



I'OXJ^RO DAIRY INSTRUMENTS 

Foxboro Dairy Instruments are furnished in the 
standard white-enameled, round-form, dust-proof, mois- 
ture-proof case, as illustrated. Full nickel plate or 
other finishes can be supplied to match existing equip- 
ment. Sanitary fittings are supplied to suit any stand- 
ard make of pasteurizer. 

Figure 1 — ■ Foxboro Automatic Temperature Re- 
corder-Controller for the dairy. Combines temperature 
controller and recording thermometer. Particularly valu- 
able for regulating and recording temperature in pas- 
teurizers, storage rooms, hardening rooms, drying kilns, 
drying rooms, curing rooms, or wherever it is desired 
to keep a careful check on holding temperatures and 
maintain permanent records of these temperatures. 

Figure 2 — Foxboro Automatic Temperature Con- 
troller for dairy use wherever it is desired to main- 
tain a definite temperature without keeping a record of 
the temperature. 

Figure 3 — Foxboro Long-Distance Dial-Type Dairy 
Indicating Thermometer used extensively on pre-heaters, 
cookers, tanks, washers and other equipment if no record 
is desired. It replaces the ordinary glass thermome- 
ter, eliminating breakage and mercury contamination. 
The instrument shown is provided with double electric 
alarm attachment for giving a warning signal when 
the temperature rises to a certain point or falls below 
a certain point. This device is also provided on re- 
cording instruments. 

Figure 4 — Foxboro Long-Distance Recording Dairy 
Thermometer. For every required temperature range 
in the Dairy Industry. Used in bacteriological labora- 
tories, on pasteurizers, receiving vats, pre-heaters, 
coolers, holding tanks, storage rooms, ripeners, ageing 
tanks, freezers, brine tanks, hardening rooms, sterilizers, 
condensers, drying kilns, drying rooms, cheese vats, 
curing rooms and in the refrigerating plant. 

Figure 5 — Foxboro Recording Pressure and Vac- 
uum Gauge used on homogenizers, viscolizers, sterilizers, 
evaporators, vacuum pans, condensers, drying cylinders 
and steam lines. 



74 Controller and Thermometer Bulbs 




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76 



Power Plant Instruments 




Some Foxboro Power Plant Instruments 



Power Plant Instruments 77 



JlOXBORO 

POWER PLANT INSTRUMENTS 

P'igures 1 & 2 — Foxboro Recording and Indicat- 
ing Thermometers for power plants. Used on feed- 
water heaters, stacks, economizers, steam lines, ammonia 
compressors, freezing tanks, condensers, forecoole'rs, 
brine lines, brine tanks. 

Figures 3 & 4 — Foxboro Recording and Indicat- 
ing Pressure Gauges for power plants. For use on 
boilers, steam lines, liquid lines and compressors. 

Figure 5 — Foxboro Two-Pen Recording Pres- 
sure Gauges for recording compressor suction and dis- 
charge pressures. Low pressure two-pen" recorders are 
used for recording draft at any two parts of the boiler 
system. 

For dairies whose power requirements necessitate 
plants of large capacity Foxboro-Heath COg Recorders 
produce permanent records of the COo content in the 
flue gases. Their use greatly increases the efficiency and 
economy of plant operation. For large plants we 
also recommend the use of Foxboro Triplex Draft 
Gauges for indicating pit pressure, draft in the last 
pass and in the furnace above the fire. Although this in- 
strument was only recently placed on the market its 
accuracy, compactness and easy reading quality have 
made it exceedingly popular with engineer and fireman. 

Write us for further information concerning these 
instruments. 



Legal Standards for Dairy Products 







2 






Condensed Milk 


r^"'' 1 Ci 
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Milk 


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lEESE 






States 








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Arizona . . . 




8.5 


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18 


80. 16 


7.7 28. 


7.7 


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Arkansas t . . ■ 




























California . . . 


n.5 


8.5 13. 


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Colorado . . . 


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Connecticut . 


11.75 8.5 3.25 






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12.5 9. 3.5 


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Florida * . . 


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11.76 8.5 3.25 


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Illinois . . . 


. . . 8.5 3. 


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Iowa .... 


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Wyoming . . . 




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7.8 26.5 


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U. S. Dept. of 




























Agriculture 


1 




18 


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* U. S. Department of Agriculture Standards, 
t No State Standards. 

Note: — U. S. Department of Agriculture Standards for milk: Milk is the whole, fresh, 
clean, lacteal secretion obtained by the complete milking of one or more healthy cows, properly 
fed and kept, excluding that obtained within fifteen days before and five days after calving, or 
such longer period as may be necessary to render the milk practically colostrum free. 

Pasteurized Milk is milk that has been subjected to a temperature not lower than 145 de- 
grees Fahrenheit for not less than thirty minutes. Unless it is bottled hot, it is promptly 
cooled to 60 degrees Fahrenheit or lower. 



INDEX 



Ageing the Mix 43 

Alarm Attachment for Thermometers. . 72, 73 
Automatic Temperature Controller. . . . 72, 73 
Automatic Temperature Recorder-Con- 
troller 72, 73 

Bacteria, Effect of Temperature on 2 

Bacteriology 9 

Board of Health Regulations 26, 29 

Boiler Room Instruments 69, 76, 77 

Boiling Points of Water at Different 

Vacua 50 

Bottle Method of Pasteurization 28 

Brine, Properties of 43 

Bulbs, Controller and Thermometer. . . 74, 75 

Bulgaricus Starter 16 

Butter Making 19 

Butter Storage 24 

Buttermilk, Commercial Preparation of. . 17 

CO2 Recorder 69, 77 

Casein 65 

Cheese 59 

Cheese, Culture for 16 

Cheese, Classification According to Coun- 
try of Origin 60 

Cheese, Classification According to Method 

of Ripening. 60 

Cheese, Classification According to Mois- 
ture Content 60 

Cheese Ripening, Influence of Humidity 

on _. 5 

Cherry Pasteurizer, Thermometer Bulbs 

for. 74, 75 

Chloride of Calcium, Properties of 43 

Churning 22 

Clarifier, Operation of 27 

Cleanliness in Starter Preparation 12 

Coagulation of Starter 16 

Condensation 50 

Condensation, Amount of 51 

Condensed and Evaporated Milk 48 

Condensed Buttermilk . 55 

Continuous Evaporators 54 

Controller Bulbs 74, 75 

Controllers, Automatic Temperature. . . 72, 73 

Cooling after Pasteurization 30 

Cooling Condensed Milk 51 

Cream 26 

Cream, Separation for Butter Making. . . 19 

Cream Separator, Efficiency of 19 

Cream Standardization 31 

Culture, Adding the 13 

Curd, Preparation of 61 

Dairy Instruments 72, 73 

Davis Pasteurizer, Thermometer Bulbs 

for. . . 74,75 

Deterioration in Storage 4 

Dial-Type Thermometers, Dairy 72, 73 

Draft Gauges 76, 77 

Drying Casein 66 

Drying of Cheese 62 

Drying of Milk Sugar 66 

Economy Pasteurizer, Thermometer Bulbs 

for 74. 76 



Page 

Ekenberg Process 57 

Electric Alarm Attachment for Thermom- 
eters 72, 73 

Elyria Pasteurizer, Thermometer Bulbs 

for 74, 75 

Emulsifiers 41 

Evaporated Milk 48 

Evaporated Milk Processing and Steri- 
lizing 52 

Federal Requirements for Condensed and 

P>aporated Milk 53 

Federal Standards tor Dairy Products ... 78 

Flash Method of Pasteurization 28 

Flavor, Influence of Temperature on 3 

Freezing of Ice Cream 45 

Gauges, Dairy Recording 72, 73 

Gauges, Pressure, Recording and Indi- 
cating for Power Plants 69, 76, 77 

Gauges, Two-Pen Pressure, Record- 
ing 69, 76, 77 

Gray Process 58 

Hardening of Ice Cream 46 

Hatmaker Process 56 

Holding of Milk after Pasteurization 30 

Holding Method of Pasteurization 28 

Homogenizers 41 

Humidity in Cheese Curing Rooms 63 

Humidity, Influence of, on Dairy Oper- 
ations 5 

Ice Cream 39 

Ice Cream Recipes 40 

Incubating Process, Temperature Rec- 
ords of 9 

Incubation, Effect of Temperature on. ... 10 
Indicating Instruments, Power Plant 68, 76, 77 

Indicating Thermometers, Dairy 72, 73 

Instruments, Power Plant 68, 76, 77 

Keeping Quality of Milk, Effect of Tem- 
perature on 2 

Lactic Acid Starter 10 

Legal Standards of Dairy Products 78 

Long-Distance Thermometers, Dairy 72, 73 

Merrell-Soule Process 57 

Micro-Organisms, Effect of Temperature 

on 1 

Micro-Organisms, Growth of, in Dairy 

Products 2 

Milk 26 

Milk Powder 56 

Milk Powder, Definition of 58 

Milk Sugar 66 

Milk Standardization SO 

Mixing 41 

Mixing Machinery for Ice Cream Plants 41 

Moisture Content of Cheeses 60 

"Mother" Starter 13, 15 



INDEX — Continued 



Page 
Open Vats, Thermometer Bulbs for. ... 74, 75 
Over-run 

Paraffining of Cheese 64 

Pasteurization *° 

Pasteurization for Ice Cream Plants 40 

Pasteurization of Cream for Butter Makmg 20 

Pasteurization of Starter Milk . H 

Pfaudler Pasteurizer, Thermometer Bulb 

for 74,75 

Power Plant, Dairy ■ ■ • ■ 67 

Power Plant Instruments 68, 7b, 77 

Pre-Heating of Milk ■ ■ 26 

Pressure (lauges, Recording, for Boiler 

Rooms 69,76,77 

Pressure, Influence of, on Dairy Oper- 
ations ^ 

Pressure, Vacuum Pan _■ *'' 

Pressure, Viscolizing or Homogenizing ... H 

Propagation, The Second Day's 14 

Psychrometer, Recording 63 

Quality Instruments, Value of 70 

Quality of Products, Effect of Temper- 
ature oil 3 

Ranges, Pasteurizer Thermometer 75 

Recipes for Ice Cream 40 

Recorder, CO2 69,77 

Recording Gauges, Dairy '^^' Z, 

Recording Instruments, Power Plant 68, 76, 77 
Recording Instruments, Value of, in Power 

Plants 70 

Recording Thermometers, Dairy 72, 73 

Rectangle Method of Standardizing 31 

Refrigeration of Condensed Milk 52 

Refrigeration, Importance of, in Ice Cream 

Making 39 

Refrigerating Room Instruments. . . 69, 76, 77 
Rennet, Addition 01, in Cheese Making 62 

Ripening, Cheese 63 

Ripening Methods, Cheese 60 

Ripening of Cream 20 

Salt Solutions, Properties of 43 

Salting of Butter 23 

Salting of Cheese 62 

Simplex Pasteurizer, Thermometer Bulbs 

for 74.75 

Souring of Ice Cream Mix 44 

Specific Gravity of Milk and Cream 37 

Standardizing Milk and Cream 31 

Standards for Dairy Products, U. S. Dept. 

of Agriculture 78 

Starter , 10, 15, 21 

Starter Milk, Selection of 11 



Page 

Startoline 1^ 

State Standards for Dairy Products 78 

Sterilizing of Evaporated Milk 52 

Storage, Influence of Temperature on. . . . 4 

Storage of Butter 24 

Storage of Cheese 64 

Superheated Condensed Milk 61 

Swell, How to Obtain 46 

Temperature, Casein Dry-Kiln 66 

Temperature, Cheese Curing Room 63 

Temperature, Churning •,. ' ' ' *^ 

Temperature, Condensed Milk CooUng. . 51 

Temperature, Condensing Water 51 

Temperature, Cooling ^0 

Temperature Curd is Cooked in Cheese 

Making 63 

Temperature, Ekenberg Process 67 

Temperature, Emulsifying •,.••;• *1 

Temperature, Hatmaker Process Cyhnders 56 

Temperature, Ice Cream Freezing 45 

Temperature, Ice Cream Hardening Room 47 

Temperature, Ice Cream Mix 44 

Temperature, Influence of, on Dairy Oper- 
ations 1' 3> 4 

Temperature, Milk Holding 30 

Temperature, Milk Sugar Drying Room 66 

Temperature, Pasteurizing 28 

Temperature, Pre-Heating 26 

Temperature, Refrigeration, of Condensed 

Milk ••■••■ S2 

Temperature, Rennet is Added in Cheese 

Making • • 62 

Temperature, Sterilizing of Evaporated 

Milk 62 

Temperature, Vacuum Pan 49 

Texture, Influence of Temperature on 3 

Thermometer Bulbs '^*'V 

Thermometers, Dairy Recording ■ ■ . • ■. 72, 78 
Thermometers, Recording and Indicating, 

for Boiler Rooms 69, 76, 77 

Thermometers, Recording and Indicating, 

for Refrigerating Rooms 69, 76, 77 

Triplex Draft Gauges 76, 77 

U. S. Department of Agriculture Stand- 
ards for Dairy Products 78 

Vacuum Gauges, Dairy Recording 72, 73 

Vacuum Pan Temperatures 49 

Viscolizers 41 

Washing of Butter 22 

Weight of Milk and Cream 37 

Whey Butter ■ ■• • • 24 

Wizard Pasteurizer, Thermometer Bulbs 
tor 74,76 



